Device and method for controlling communication of downlink data

ABSTRACT

There is provided a device including a control unit that controls transmission of downlink data in a manner that the transmission of the downlink data is performed using a first frequency band shared by a plurality of wireless communication systems including a cellular system. The control unit controls retransmission of the downlink data in a manner that the retransmission of the downlink data is performed using a second frequency band for the cellular system.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. application Ser. No.16/274,377 filed on Feb. 13, 2019, which is a continuation of U.S.application Ser. No. 15/505,133 filed on Feb. 20, 2017, now U.S. Pat.No. 10,225,857, which is a National Stage Entry of PCT/JP2015/067913filed on Jun. 22, 2015, which claims priority benefit of Japanese PatentApplication No. JP 2014-174905 filed in the Japan Patent Office on Aug.29, 2014. Each of the above-referenced applications is herebyincorporated herein by reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a device and a method.

BACKGROUND ART

In the 3^(rd) Generation Partnership Project (3GPP), varioustechnologies for improving system throughput have been discussed. It maybe said that a first shortcut for improving the system throughput isincreasing a frequency to be used. In the 3GPP, the technology ofcarrier aggregation (CA) has been considered in Release 10 and Release11. CA is a technology for improving the system throughput and a maximumdata rate by aggregating component carriers (CCs) having a bandwidth of20 MHz for use. A frequency band available as a CC must adopt thetechnology of such CA. Thus, a frequency band available for wirelesscommunication of a cellular system is required.

For example, in Patent Literature 1, technology which enables aregistered frequency band available for a registered provider and anunlicensed band available when a predetermined condition is satisfied tobe used in addition to a dedicated frequency band allocated to eachprovider for exclusive use is disclosed.

CITATION LIST Patent Literature

Patent Literature 1:

-   JP 2006-094001A

DISCLOSURE OF INVENTION Technical Problem

When a frequency band shared by a plurality of wireless communicationsystems (that is, a frequency band of an unlicensed band) is used in acellular system, for example, a base station transmits downlink datausing the frequency band. The base station can perform retransmission ofthe downlink data using the frequency band as well.

However, when the frequency band shared by a plurality of wirelesscommunication systems is used, it may be difficult to performretransmission of the downlink data. As an example, since the frequencyband is also used in other wireless communication systems, the frequencyband can be used in the cellular system at the time of transmission ofdownlink data, but it is not necessarily possible to use the frequencyband in the cellular system at the time of retransmission of thedownlink data. There may be cases in which long-term use of thefrequency band is not permitted. As another example, since the frequencyband (for example, a channel of a wireless LAN) is also used in otherwireless communication system (for example, the wireless LAN), when asignal of the cellular system is transmitted using the frequency band,the signal may collide with signals of the other wireless communicationsystems. For this reason, the downlink data may not be appropriatelytransmitted and received.

In this regard, it is desirable to provide a mechanism which is capableof retransmitting downlink data with a high degree of certainty when afrequency band shared by a plurality of wireless communication systemsis used in a cellular system.

Solution to Problem

According to the present disclosure, there is provided a device,including: a control unit configured to control transmission of downlinkdata in a manner that the transmission of the downlink data is performedusing a first frequency band shared by a plurality of wirelesscommunication systems including a cellular system. The control unitcontrols retransmission of the downlink data in a manner that theretransmission of the downlink data is performed using a secondfrequency band for the cellular system.

According to the present disclosure, there is provided a method,including: controlling, by a processor, transmission of downlink data ina manner that the transmission of the downlink data is performed using afirst frequency band shared by a plurality of wireless communicationsystems including a cellular system; and controlling, by the processor,retransmission of the downlink data in a manner that the retransmissionof the downlink data is performed using a second frequency band for thecellular system.

According to the present disclosure, there is provided a device,including: a control unit configured to perform a receiving side processin a retransmission control process according to transmission ofdownlink data performed by a base station using a first frequency bandshared by a plurality of wireless communication systems including acellular system. The control unit performs the receiving side process inthe retransmission control process according to retransmission of thedownlink data performed by the base station using a second frequencyband for the cellular system.

According to the present disclosure, there is provided a method,including: performing, by a processor, a receiving side process in aretransmission control process according to transmission of downlinkdata performed by a base station using a first frequency band shared bya plurality of wireless communication systems including a cellularsystem; and performing, by the processor, the receiving side process inthe retransmission control process according to retransmission of thedownlink data performed by the base station using a second frequencyband for the cellular system.

Advantageous Effects of Invention

As described above, according to the present disclosure, it is possibleto retransmit downlink data with a high degree of certainty when afrequency band shared by a plurality of wireless communication systemsis used in a cellular system. Note that the effects described above arenot necessarily limited, and along with or instead of the effects, anyeffect that is desired to be introduced in the present specification orother effects that can be expected from the present specification may beexhibited.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is an explanatory diagram illustrating a frame format ofInstitute of Electrical and Electronics Engineers (IEEE) 802.11.

FIG. 2 is an explanatory diagram illustrating a frame format oflong-term evolution (LTE).

FIG. 3 is an explanatory diagram for describing an example ofretransmission control in the case of carrier aggregation.

FIG. 4 is an explanatory diagram for describing an example ofretransmission control in the case of dual connectivity.

FIG. 5 is an explanatory diagram for describing an example of a DCIformat.

FIG. 6 is an explanatory diagram illustrating an example of a schematicconfiguration of a system according to an embodiment of the presentdisclosure.

FIG. 7 is a block diagram illustrating an example of a configuration ofa base station according to the embodiment.

FIG. 8 is a block diagram illustrating an example of a configuration ofa terminal device according to the embodiment.

FIG. 9 is an explanatory diagram for describing an example oftransmission and retransmission of downlink data according to theembodiment.

FIG. 10 is an explanatory diagram for describing an example of use of ashared band by a base station.

FIG. 11 is an explanatory diagram for describing a first example of alimited period in which retransmission of downlink data is performedusing a cellular band.

FIG. 12 is an explanatory diagram for describing a second example of alimited period in which retransmission of downlink data is performedusing a cellular band.

FIG. 13 is an explanatory diagram for describing a first example oftransmission of an ACK/NACK in response to downlink data.

FIG. 14 is an explanatory diagram for describing a second example oftransmission of an ACK/NACK in response to downlink data.

FIG. 15 is an explanatory diagram for describing an example of apredetermined DCI format.

FIG. 16 is an explanatory diagram for describing a first example oftransmission of DCI according to retransmission of downlink data.

FIG. 17 is an explanatory diagram for describing a second example oftransmission of DCI according to retransmission of downlink data.

FIG. 18 is an explanatory diagram for describing a third example oftransmission of DCI according to retransmission of downlink data.

FIG. 19 is a flowchart illustrating an example of a schematic flow of aprocess of a base station according to the embodiment.

FIG. 20 is a flowchart illustrating an example of a schematic flow of afirst process of a terminal device according to the embodiment.

FIG. 21 is a flowchart illustrating an example of a schematic flow of asecond process of a terminal device according to the embodiment.

FIG. 22 is an explanatory diagram for describing an example of a basestation according to a modified example of the embodiment.

FIG. 23 is a block diagram illustrating a first example of a schematicconfiguration of an eNB.

FIG. 24 is a block diagram illustrating a second example of a schematicconfiguration of an eNB.

FIG. 25 is a block diagram illustrating an example of a schematicconfiguration of a smartphone.

FIG. 26 is a block diagram illustrating an example of a schematicconfiguration of a car navigation device.

MODE(S) FOR CARRYING OUT THE INVENTION

Hereinafter, preferred embodiments of the present disclosure will bedescribed in detail and with reference to the attached drawings. Notethat, in this specification and the appended drawings, structuralelements that have substantially the same function and structure aredenoted with the same reference numerals, and repeated explanation ofthese structural elements is omitted.

Also, the description will be given in the following order.

1. Introduction

2. Schematic configuration of system

3. Configuration of each device

3.1. Configuration of base station

3.2. Configuration of terminal device

4. Technical characteristics according to embodiment of presentdisclosure

4.1. Technical characteristics regarding base station

4.2. Technical characteristics regarding terminal device

5. Flow of process

6. Modified examples

7. Application examples

7.1. Application examples regarding base station

7.2. Application examples regarding terminal device

8. Conclusion

«1. Introduction»

First, sharing of a frequency band, technology related to wirelesscommunication, and technology related to a cellular system will bedescribed with reference to FIGS. 1 to 5.

(Sharing of Frequency Band)

(a) Background of Frequency Sharing

A frequency band available for the cellular system is required. Forexample, a band of 5 GHz is considered as a frequency band for use inthe cellular system.

However, the band of 5 GHz is also used in the wireless LAN. Thus, whenthe cellular system uses the band of 5 GHz, for example, the band of 5GHz is shared between cellular system and wireless LAN. Specifically,for example, a frequency band of 5 GHz (for example, a channel of awireless LAN) is used in the wireless LAN communication at a certaintime and used in the cellular system at another time. Thereby, frequencyutilization efficiency of the band of 5 GHz is improved. Also, thewireless LAN standard includes Institute of Electrical and ElectronicsEngineers (IEEE) 802.11a, 11b, 11g, 11n, 11 ac, and 11 ad, etc. andthese standards are characterized in that IEEE 802.11 is adopted for amedia access control (MAC) layer.

(b) Sharing Technique

Wireless LAN nodes (an access point and a station) are alreadywidespread around the world. For this reason, from the point of view ofbackward compatibility, it is desirable for a mechanism for sharing afrequency band between a cellular system and a wireless LAN that doesnot change operations of the wireless LAN nodes to be reviewed as atechnique of Long Term Evolution (LTE) and decided as a new standard ofLTE. A terminal device conforming to the new standard is considered touse a frequency band shared between the cellular system and the wirelessLAN (hereinafter referred to as a “shared band”), while a terminaldevice not conforming to the new standard is considered not to use theshared band.

(c) Usage as Component Carrier

In LTE, LTE-Advanced, or a cellular system conforming to a communicationstandard equivalent thereto, the shared band will be used as, forexample, a component carrier (CC). Further, it is assumed that thefrequency band of the cellular system is used as a primary componentcarrier (PCC) and the shared band is used as a secondary componentcarrier (SCC). Also, a control signal and a data signal can betransmitted and received using a frequency band of the cellular systemand the data signal can be transmitted and received using the sharedband.

(d) Fair Sharing

It is desirable for the shared band to be fairly shared between thecellular system and the wireless LAN. In the wireless LAN, since achannel (the shared band) is fairly shared according to carrier sensemultiple access (CSMA), it is desirable for the channel (the sharedband) to be fairly shared, for example, even between the cellular systemand the wireless LAN through a technique in which CSMA is considered.

Various sharing techniques can be considered as fair sharing. Forexample, fair sharing can be defined as “the case in which opportunitiesfor the wireless LAN to use the shared band and opportunities for thecellular system to use the shared band are equally given.” In otherwords, it does not means that the cellular system and the wireless LANare the same in actual communication traffic, and any case in which thesame opportunities of communication are given to the cellular system andthe wireless LAN is regarded as fair sharing.

As an example, when the shared band is used in the cellular system for acertain period, then the shared band is not used in the cellular systemfor the same period.

(Technology Related to Wireless LAN)

A frame format of IEEE 802.11 will be described as the technologyrelated to wireless LAN with reference to FIG. 1. FIG. 1 is anexplanatory diagram illustrating a frame format of IEEE 802.11.

In IEEE 802.11, a DATA frame and an acknowledgement (ACK) frame arebasic frames. When the DATA frame is correctly received, the ACK frameis a frame which causes a transmitting side to know the success ofreception of the DATA frame. Although wireless communication can beperformed only by the DATA frame and the ACK frame in the wireless LAN,two frames such as a request to send (RTS) frame and a clear to send(CTS) frame are generally further used.

Before the RTS frame is transmitted, each wireless LAN node whichperforms the wireless LAN communication confirms that no signal istransmitted during a period referred to as a distributed coordinationfunction (DCF) inter-frame space (DIFS). This is referred to as carriersense. When nodes simultaneously start to transmit signals at a point intime at which the DIFS has elapsed, the signals may collide with eachother. Thus, each node waits for a backoff time randomly set for eachnode and transmits a signal if no signal is transmitted for the backofftime.

Basically, the node cannot transmit the signal while any signal isdetected. However, because there is a hidden terminal problem, an RTSframe and a CTS frame including a duration field for setting a valuereferred to as a network allocation vector (NAV) are added. The NAV isset on the basis of a value included in the duration field. The nodesetting the NAV avoids transmitting a signal during a period of the NAV.

First, a first node for transmitting the DATA frame transmits the RTSframe. Then, another node located around the first node receives the RTSframe and acquires a value included in the duration field in the RTSframe. The other node sets, for example, its own NAV to theabove-mentioned acquired value and avoids transmitting a signal duringthe period of the NAV. For example, the period of the NAV is a periodfrom the end of the RTS frame to the end of the ACK frame.

Also, a second node for receiving the DATA frame transmits the CTS frameafter only a short inter-frame space (SIFS) from the end of the RTSframe according to the reception of the RTS frame. Then, another nodelocated around the above-mentioned second node receives the CTS frameand acquires a value included in the duration field in the CTS frame.The other node sets, for example, its own NAV to the above-mentionedacquired value and avoids transmitting a signal during the period of theNAV. The period of the NAV is a period from the end of the CTS frame tothe end of the ACK frame. Thereby, for example, it is possible toprevent the other node (that is, a hidden node for the above-mentionedfirst node) close to the above-mentioned second node without being closeto the above-mentioned first node from transmitting a signal duringcommunication of the above-mentioned first node and the above-mentionedsecond node.

Also, the RTS frame includes a frame control field, a reception addressfield, a transmission address field, and a frame check sequence (FCS) inaddition to the duration field. Also, the CTS frame includes a framecontrol field, a reception address field, and an FCS in addition to theduration field.

Also, the DIFS and the SIFS in the standard of the IEEE 802.11 serieshave, for example, the following lengths.

TABLE 1 802.11b 802.11g 802.11a 802.11n 802.11ac SIFS 10 us 10 us 16 us16 us 16 us DIFS 50 us 28 us 34 us 34 us 34 us(Technology Related to Cellular System)

(a) Frame Format

The frame format of LTE will be described with reference to FIG. 2. FIG.2 is an explanatory diagram illustrating the frame format of LTE.

First, a unit of time such as a radio frame is used in LTE. One radioframe is 10 ms. Each radio frame is identified by a system frame number(SFN) which is any one of 0 to 1023.

The radio frame includes 10 sub-frames identified by #0 to #9. Eachsub-frame is 1 ms. Further, each sub-frame includes two slots and eachslot includes, for example, seven orthogonal frequency divisionmultiplexing (OFDM) symbols. That is, each sub-frame includes 14 OFDMsymbols. Also, the frame format illustrated in FIG. 2 is a frame formatof a downlink and the frame format of an uplink includes a singlecarrier frequency division multiple access (SC-FDMA) symbol in place ofan OFDM symbol.

(b) Carrier Aggregation

-   Component Carriers    With carrier aggregation in Release 10, up to a maximum of five CCs    are aggregated for use by user equipment (UE). Each CC is a band    with a maximum width of 20 MHz. Carrier aggregation includes a case    in which successive CCs in the frequency direction are used, and a    case in which separated CCs in the frequency direction are used.    With carrier aggregation, the CCs to be used may be set for each UE.

PCC and SCC

In carrier aggregation, one of the multiple CCs used by a UE is aspecial CC. This special CC is called the primary component carrier(PCC). Also, the remaining CCs among the multiple CCs are calledsecondary component carriers (SCCs). The PCC may be different dependingon the UE.

Since the PCC is the most important CC among the multiple CCs, it isdesirable for the PCC to be the CC with the most stable communicationquality. Note that in actual practice, which CC to treat as the PCCdepends on the implementation.

The SCC is added to the PCC. In addition, an existing SCC that has beenadded may also be removed. Note that changing an SCC is conducted byremoving an existing SCC and adding a new SCC.

PCC Determination Method and Changing Method

When a UE connection is initially established and the status of the UEgoes from Radio Resource Control (RRC) Idle to RRC Connected, the CCthat the UE used during the establishment of the connection becomes thePCC for that UE. More specifically, a connection is established througha connection establishment procedure. At this point, the status of theUE goes from RRC Idle to RRC Connected. Also, the CC used in theprocedure becomes the PCC for the above UE. Note that the aboveprocedure is a procedure initiated from the UE side.

Additionally, PCC changing is conducted by a handover betweenfrequencies. More specifically, if a handover is specified in aconnection reconfiguration procedure, a PCC handover is conducted, andthe PCC is changed. Note that the above procedure is a procedureinitiated from the network side.

-   -   Adding SCC        As discussed above, the SCC is added to the PCC. As a result,        the SCC is associated with the PCC. In other words, the SCC is        subordinate to the PCC. SSC addition may be conducted through a        connection reconfiguration procedure. Note that this procedure        is a procedure initiated from the network side.    -   Removing SSC        As discussed above, an SCC may be removed. SSC removal may be        conducted through a connection reconfiguration procedure.        Specifically, a specific SCC specified in a message is removed.        Note that the above procedure is a procedure initiated from the        network side.

In addition, the removal of all SCCs may be conducted through aconnection re-establishment procedure.

Special Role of PCC

The connection establishment procedure, the transmitting and receivingof non-access stratum (NAS) signaling, and the transmitting andreceiving of uplink control signals on the physical uplink controlchannel (PUCCH) are conducted only by the PCC, and not by the SCCs.

In addition, the detection of a radio link failure (RLF) and asubsequent connection re-establishment procedure are also conducted onlyby the PCC, and not by the SCCs.

(Conditions of Backhauling for Carrier Aggregation)

For example, an ACK of a downlink signal on an SCC is transmitted by thePUCCH of the PCC. Since the ACK is used for the retransmission of databy the evolved Node B (eNB), a delay of the ACK is not acceptable.Consequently, when a first eNB using a CC that acts as the PCC for a UEis different from a second eNB using a CC that acts as an SCC for theUE, a backhaul delay of approximately 10 ms between the first eNB andthe second eNB is desirable.

(c) HARQ

In LTE, a hybrid automatic repeat request (HARQ) is used as aretransmission control mechanism.

HARQ Process

For example, an eNB transmits data, and a UE receives the data. When anerror is detected through a cyclic redundancy check (CRC) or the like,the UE transmits a negative acknowledgement (NACK) through an uplink.Upon receiving the NACK, the eNB retransmits the data, and the UEreceives the data. When no error is detected through the CRC or the like(that is, when downlink data is properly received), the UE transmits anacknowledgement (ACK) through an uplink. Upon receiving the ACK, the eNBtransmits new data. Such a data transmission/reception process is calleda stop and wait (SAW) process. Particularly, in the case of the HARQ,the SAW process is also called a HARQ process. In one HARQ process, newdata is not transmitted until the UE properly receives data. Further,for one UE, a plurality of HARQ processes are simultaneously performed.

A timing at which an ACK/NACK is transmitted for downlink data is notdefined in the standard of LTE, and thus there is flexibility. However,when retransmission is delayed, data is delayed, and thus it isdesirable to transmit an ACK/NACK as quickly as possible.

Case of Carrier Aggregation

In the case of the carrier aggregation, there is a HARQ entity for eachcomponent carrier (CC). The HARQ entity handles a plurality of HARQprocesses for a corresponding CC.

An ACK/NACK is transmitted through a physical uplink control channel(PUCCH). In the case of carrier aggregation, the UE is able to transmitan ACK/NACK through the PUCCH of the primary component carrier (PCC) butunable to transmit an ACK/NACK through the PUCCH of the secondarycomponent carrier (SCC). For this reason, an ACK/NACK for downlink datatransmitted using the SCC is transmitted through the PUCCH of the PCC.Further, retransmission of the downlink data transmitted using the SCCis performed using the SCC. Understandably, retransmission of thedownlink data transmitted using the PCC is performed using the PCC. Thispoint will be described below with reference to FIG. 3 using a specificexample.

FIG. 3 is an explanatory diagram for describing an example ofretransmission control in the case of carrier aggregation. Referring toFIG. 3, the PCC and the SCC are illustrated. The eNB performstransmission of downlink data using the PCC, and the UE transmits anACK/NACK for the downlink data using the PCC. When the ACK for thedownlink data is not received, the eNB performs retransmission of thedownlink data using the PCC. Further, the eNB performs transmission ofdownlink data using the SCC, and the UE transmits the ACK/NACK for thedownlink data using the PCC rather than the SCC. When the ACK for thedownlink data is not received, the eNB performs retransmission of thedownlink data using the SCC.

In the future, dual connectivity may be introduced. In this case, the UEcan transmit an ACK/NACK using both of the two CCs. This point will bedescribed below with reference to FIG. 4 using a specific example.

FIG. 4 is an explanatory diagram for describing an example ofretransmission control in the case of dual connectivity. Referring toFIG. 4, a first CC and a second CC are illustrated. The UE supports dualconnectivity and uses, for example, each of the first CC and the secondCC as the PCC. The eNB performs transmission of downlink data using thefirst CC, and the UE transmits an ACK/NACK for the downlink data usingthe first CC. When the ACK for the downlink data is not received, theeNB performs retransmission of the downlink data using the first CC.Further, the eNB performs transmission of downlink data using the secondCC, and the UE transmits the ACK/NACK for the downlink data using thesecond CC. When the ACK for the downlink data is not received, the eNBperforms retransmission of the downlink data using the second CC.

As described above, in any case, the same frequency band (for example,CC) is used for transmission and retransmission of downlink data.

(d) Downlink Control Information

The eNB transmits downlink control information (DCI) fortransmission/retransmission of downlink data at the time oftransmission/retransmission of downlink data. In LTE, each piece of DCIis information according to one of a plurality of DCI formats. Anexample of the DCI format will be described below.

FIG. 5 is an explanatory diagram for describing an example of the DCIformat. Referring to FIG. 5, the DCI format is illustrated. For example,the DCI format includes fields such as a carrier indicator, resourceblock allocation, a HARQ process number, and a new data indicator (NDI).The carrier indicator field (CIF) is a field indicating a componentcarrier in the case of carrier aggregation. The resource blockallocation field is a field indicating resource blocks allocated to theUE (that is, resource blocks allocated for transmission of downlinkdata). The HARQ process number field is a field indicating the HARQprocess for downlink data. The NDI field is a field indicating whetherthe reason for resource allocation is transmission of new data orretransmission.

«2. Schematic Configuration of System»

Next, a schematic configuration of a system according to an embodimentof the present disclosure will be described with reference to FIG. 6.FIG. 6 is an explanatory diagram illustrating an example of a schematicconfiguration of a system 1 according to an embodiment of the presentdisclosure. Referring to FIG. 6, the system 1 includes a base station100 and a terminal device 200.

(Base Station 100)

The base station 100 is a base station of the cellular system. Forexample, the cellular system is a system conforming to LTE,LTE-Advanced, and a communication standard equivalent thereto.

(a) Frequency Band

Cellular Band

The base station 100 performs wireless communication using a frequencyband for the cellular system (hereinafter referred to as a “cellularband”). For example, the cellular band is a component carrier (CC) forthe cellular system.

The cellular band is a licensed band or a frequency band included in thelicensed band.

Shared Band

Particularly, in an embodiment of the present disclosure, the basestation 100 further performs wireless communication using a frequencyband shared by a plurality of wireless communication systems includingthe cellular system (hereinafter referred to as a “shared band”).

As an example, a plurality of wireless communication systems include thewireless LAN, and the shared band is the channel of the wireless LAN.More specifically, for example, the shared band is a channel of a bandof 5 GHz (or a band of 2.4 GHz) and a bandwidth of 20 MHz. It will beappreciated that the shared band is not limited to this example and maybe any other frequency band which is shared by a plurality of wirelesscommunication systems.

The shared band is an unlicensed band or a frequency band included inthe unlicensed band.

(b) Wireless Communication with Terminal Device

The base station 100 performs wireless communication with a terminaldevice (for example, the terminal device 200). For example, the basestation 100 performs wireless communication with a terminal devicelocated within a cell 10 of the base station 100. More specifically, forexample, the base station 100 transmits a downlink signal to theterminal device, and receives an uplink signal from the terminal device.

(Terminal Device 200)

For example, the terminal device 200 performs wireless communicationwith a base station (for example, the base station 100). For example,when the terminal device 200 is located within a cell of a base station(for example, the cell 10 of the base station 100), the terminal device200 performs wireless communication with the base station. Specifically,for example, the terminal device 200 receives the downlink signal fromthe base station and transmits the uplink signal to the base station.

The terminal device 200 performs wireless communication with the basestation 100 using the cellular band. Particularly, in an embodiment ofthe present disclosure, the terminal device 200 further performswireless communication with the base station 100 using the shared band.

For example, the terminal device 200 supports carrier aggregation. Inother words, the terminal device 200 can perform wireless communicationusing two or more component carriers (CC) at the same time.

«3. Configuration of Each Device»

Next, an example of configurations of the base station 100 and theterminal device 200 according to an embodiment of the present disclosurewill be described with reference to FIGS. 7 and 8.

<3.1. Configuration of Base Station>

Next, an example of the configuration of a base station 100 according toan embodiment of the present disclosure will be described with referenceto FIG. 7. FIG. 7 is a block diagram illustrating an example of theconfiguration of the base station 100 according to an embodiment of thepresent disclosure. Referring to FIG. 7, the base station 100 isequipped with an antenna unit 110, a wireless communication unit 120, anetwork communication unit 130, a storage unit 140, and a processingunit 150.

(Antenna Unit 110)

The antenna unit 110 emits a signal output by the wireless communicationunit 120 into space as a radio wave. Additionally, the antenna unit 110converts a radio wave from space into a signal, and outputs the signalto the wireless communication unit 120.

(Wireless Communication Unit 120)

The wireless communication unit 120 performs transmission and receptionof a signal. For example, the wireless communication unit 120 performstransmission and reception of a signal using the cellular band (that is,the frequency band for the cellular system) and/or the shared band (thatis, the frequency band shared by a plurality of wireless communicationsystems). For example, the wireless communication unit 120 transmits thedownlink signal to the terminal device, and receives the uplink signalfrom the terminal device.

(Network Communication Unit 130)

The network communication unit 130 performs transmission and receptionof information. For example, the network communication unit 130transmits information to another node, and receives information fromanother node. For example, another node includes another base stationand a core network node.

(Storage Unit 140)

The storage unit 140 temporarily or permanently stores programs and datafor the operation of the base station 100.

(Processing Unit 150)

The processing unit 150 provides various functions of the base station100. The processing unit 150 includes an information acquiring unit 151and a control unit 153. The processing unit 150 may further include anyother component in addition to these components. In other words, theprocessing unit 150 can perform an operation other than operations ofthese components.

(Information Acquiring Unit 151)

The information acquiring unit 151 acquires information for the controlunit 153. For example, the information acquiring unit 151 acquiresdownlink data.

(Control Unit 153)

The control unit 153 controls transmission of downlink data by the basestation 100.

<3.2. Configuration of Terminal Device>

Next, an example of the configuration of terminal device 200 accordingto an embodiment of the present disclosure will be described withreference to FIG. 8. FIG. 8 is a block diagram illustrating an exampleof the configuration of the terminal device 200 according to anembodiment of the present disclosure. Referring to FIG. 8, the terminaldevice 200 is equipped with an antenna unit 210, a wirelesscommunication unit 220, a storage unit 230, and a processing unit 240.

(Antenna Unit 210)

The antenna unit 210 emits a signal output by the wireless communicationunit 220 into space as a radio wave. Additionally, the antenna unit 210converts a radio wave from space into a signal, and outputs the signalto the wireless communication unit 220.

(Wireless Communication Unit 220)

The wireless communication unit 220 performs transmission and receptionof a signal. For example, the wireless communication unit 220 performstransmission and reception of a signal using the cellular band (that is,the frequency band for the cellular system) and/or the shared band (thatis, the frequency band shared by a plurality of wireless communicationsystems). For example, the wireless communication unit 120 receives thedownlink signal from the base station, and transmits the uplink signalto the base station.

(Storage Unit 230)

The storage unit 230 temporarily or permanently stores programs and datafor the operation of the terminal device 200.

(Processing Unit 240)

The processing unit 240 provides various functions of the terminaldevice 200. The processing unit 240 includes an information acquiringunit 241 and a control unit 243. The processing unit 240 may furtherinclude any other component in addition to these components. In otherwords, the processing unit 240 can perform an operation other thanoperations of these components.

(Information Acquiring Unit 241)

The information acquiring unit 241 acquires information for the controlunit 243.

(Control Unit 243)

The control unit 243 performs a receiving side process in aretransmission control process. For example, the retransmission controlprocess is the HARQ process.

«4. Technical Characteristics According to Embodiment of PresentDisclosure»

Next, technical characteristics according to an embodiment of thepresent disclosure will be described with reference to FIGS. 9 to 18.

<4.1. Technical Characteristics Regarding Base Station>

First, technical characteristics regarding base station 100 will bedescribed with reference to FIGS. 9 to 18.

(Retransmission of the Downlink Data)

The base station 100 performs transmission of downlink data using theshared band (that is, the frequency band shared by a plurality ofwireless communication systems including the cellular system). Thecontrol unit 153 controls transmission of downlink data in a manner thattransmission of downlink data is performed using the shared band.

Further, the base station 100 performs retransmission of the downlinkdata using the cellular band (that is, the frequency band for thecellular system). The control unit 153 controls the retransmission ofthe downlink data in a manner that the retransmission of the downlinkdata is performed using the cellular band.

In other words, the base station 100 performs transmission of downlinkdata using the shared band and performs retransmission of the downlinkdata using the cellular band.

(a) Downlink Data

For example, the downlink data is downlink data transmitted to theterminal device 200. As an example, the downlink data is a transportblock. The downlink data is not limited to this example and may be anyother data.

For example, the base station 100 transmits a first bit string generatedby encoding the downlink data in the transmission of the downlink data,and transmits a second bit string generated by encoding the downlinkdata in the retransmission of the downlink data. The second bit stringmay be the same bit string as the first bit string or may be a differentbit string from the first bit string. Specifically, chase combining maybe applied in the HARQ process, and the second bit string may be thesame bit string as the first bit string. Alternatively, incrementalredundancy may be applied in the HARQ process, and the second bit stringmay be a different bit string from the first bit string.

(b) Cellular Band and Shared Band

-   L-CC and U-CC    For example, the cellular band and the shared band are component    carriers (CCs) for the terminal device 200. As described above, the    cellular band is the licensed band or the frequency band included in    the licensed band and thus can be called a licensed component    carrier (L-CC). As described above, the shared band is the    unlicensed band or the frequency band included in the unlicensed    band and thus can be called an unlicensed component carrier (U-CC).

Carrier Aggregation

For example, the shared band is the secondary component carrier (SCC)for the terminal device 200, and the cellular band is the primarycomponent carrier (PCC) or the SCC for the terminal device 200. In otherwords, the terminal device 200 performs transmission of the downlinkdata using the shared band serving as the SCC, and performsretransmission of the downlink data using the cellular band serving asthe PCC or the SCC.

Example of Shared Band

As described above, as an example, the shared band is the channel of thewireless LAN. More specifically, for example, the shared band is achannel of a band of 5 GHz (or a band of 2.4 GHz) and has a bandwidth of20 MHz.

It will be appreciated that the shared band is not limited to thisexample and may be any other frequency band which is shared by aplurality of wireless communication systems.

(c) Example of Transmission and Retransmission

FIG. 9 is an explanatory diagram for describing an example oftransmission and retransmission of the downlink data according to anembodiment of the present disclosure. Referring to FIG. 9, the L-CC (thecellular band) and the U-CC (the shared band) are illustrated. The basestation 100 performs transmission of the downlink data using the L-CC.When an ACK for the downlink data is not received, the base station 100performs retransmission of the downlink data using the L-CC. The basestation 100 performs transmission of the downlink data using the U-CC.When the ACK for the downlink data is not received, the base station 100performs retransmission of the downlink data using the L-CC rather thanthe U-CC. As described above, transmission of the downlink data isperformed using the U-CC, but the retransmission of the downlink data isperformed using the L-CC.

(d) Example of Control

Transmission Using Shared Band

As described above, the control unit 153 controls transmission of thedownlink data in a manner that transmission of the downlink data isperformed using the shared band.

As an example, the control unit 153 controls transmission of thedownlink data by allocating radio resources (for example, resourceblocks) of the shared band to the terminal device 200 for transmissionof the downlink data. As a result, the base station 100 performstransmission of the downlink data using the shared band.

Retransmission Using Cellular Band

As described above, the control unit 153 controls the retransmission ofthe downlink data in a manner that the retransmission of the downlinkdata is performed using the cellular band.

As an example, the control unit 153 controls retransmission of thedownlink data by allocating radio resources (for example, resourceblocks) of the cellular band to the terminal device 200 forretransmission of the downlink data. As a result, the base station 100performs retransmission of the downlink data using the cellular band.

(e) Period

-   Retransmission with No Period Restriction    For example, the base station 100 performs retransmission of the    downlink data (which has been transmitted using the shared band)    using the cellular band with no period restriction. In other words,    the control unit 153 controls the retransmission of the downlink    data in a manner that the retransmission of the downlink data is    performed using the cellular band with no period restriction.

Retransmission in Limited Period

The base station 100 may perform the retransmission of the downlink data(which has been transmitted using the shared band) using the cellularband within a limited period. In other words, the control unit 153 maycontrol the retransmission of the downlink data in a manner that theretransmission of the downlink data is performed using the cellular bandwithin the limited period.

Further, the limited period may be a period corresponding to an end timeof the use of the shared band by the base station 100.

Use of Shared Band by Base Station 100

For example, the base station 100 performs wireless communication usingthe shared band in a certain period and then releases the shared bandfor other wireless communication systems. This point will be describedbelow with reference to FIG. 10 using a specific example.

FIG. 10 is an explanatory diagram for describing an example of the useof the shared band by the base station 100. In this example, the U-CC(the shared band) is the channel of the wireless LAN. The base station100 secures the U-CC (the channel of the wireless LAN) through thecarrier sense, and performs wireless communication using the U-CC in aperiod 31. Thereafter, the base station 100 releases the U-CC at leastin a period 33. In other words, the base station 100 does not use theU-CC at least in the period 33. For example, the period 31 and theperiod 33 have the same duration. As an example, the period 31 and theperiod 33 are periods of 500 ms. Accordingly, fairness is maintainedbetween the cellular system and the wireless LAN.

As described above, when the base station 100 uses the shared band in acertain period, the end time of the use of the shared band by the basestation 100 is decided according to a start time of the use of theshared band. In other words, the end time is predictable.

First Example of Limited Period

As a first example, the limited period may be a period starting at apredetermined time before the end time. This point will be describedbelow with reference to FIG. 11 using a specific example.

FIG. 11 is an explanatory diagram for describing the first example ofthe limited period in which the retransmission of the downlink data isperformed using the cellular band. Referring to FIG. 11, similarly toFIG. 10, the base station 100 performs wireless communication using theU-CC (the shared band) serving as the channel of the wireless LAN in theperiod 31, and then does not perform wireless communication using theU-CC at least in the period 33. In this case, the base station 100 usesthe L-CC (the cellular band) instead of the U-CC to performretransmission of the downlink data which has been transmitted using theU-CC within a period 37 starting at a predetermined time 35 before theend time (that is, the end time of the period 31) of the use of theU-CC. The base station 100 uses the U-CC to perform retransmission ofthe downlink data which has been transmitted using the U-CC within aperiod which is included in the period 31 but not included in the period37.

Second Example of Limited Period

As a second example, the limited period may be a period starting fromthe end time. This point will be described below with reference to FIG.12 using a specific example.

FIG. 12 is an explanatory diagram for describing the second example ofthe limited period in which the retransmission of the downlink data isperformed using the cellular band. Referring to FIG. 12, similarly toFIG. 10, the base station 100 performs wireless communication using theU-CC (the shared band) serving as the channel of the wireless LAN in theperiod 31, and then does not perform wireless communication using theU-CC at least in the period 33. In this case, the base station 100 usesthe L-CC instead of the U-CC to perform retransmission of the downlinkdata which has been transmitted using the U-CC within a period 39starting from the end time of the use of the U-CC (that is, the end timeof the period 31). The base station 100 uses the U-CC to performretransmission of the downlink data which has been transmitted using theU-CC within the period 31.

As described above, the base station 100 may perform the retransmissionof the downlink data using the cellular band instead of the shared bandwithin the period corresponding to the end time of the use of the sharedband by the base station 100. Accordingly, for example, it is possibleto prevent a situation in which the base station 100 is unable to usethe shared band and thus it is unable to perform the retransmission ofthe downlink data. Further, for example, consumption of the radioresources of the cellular band is suppressed, compared to the case inwhich the cellular band is used for retransmission of all downlink datawhich has been transmitted using the shared band.

In an embodiment of the present disclosure, the limited period is notlimited to a period corresponding to the end time. The limited periodmay be any other period.

(f) Reception of ACK/NACK

The terminal device 200 transmits an ACK/NACK for the downlink data inresponse to transmission of the downlink data by the base station 100.For example, the ACK/NACK is transmitted using the PCC of the terminaldevice 200.

First Example

As a first example, the shared band is the SCC, and the cellular band isthe PCC. In this case, an ACK/NACK for the downlink data is transmittedusing the cellular band. A specific example will be described below withreference to FIG. 13.

FIG. 13 is an explanatory diagram for describing the first example oftransmission of an ACK/NACK for the downlink data. Referring to FIG. 13,the L-CC (the cellular band) serving as the PCC and the U-CC (the sharedband) serving as the SCC are illustrated. The terminal device 200 usesthe L-CC (the PCC) to transmit the ACK/NACK for the downlink datatransmitted by the base station 100 using the L-CC. Further, theterminal device 200 uses the L-CC (the PCC) to transmit the ACK/NACK forthe downlink data transmitted by the base station 100 using the U-CC.The base station 100 uses the L-CC to perform retransmission of thedownlink data transmitted by the base station 100 using the U-CC.

Second Example

As a second example, the shared band and the cellular band may be theSCC, and other cellular bands may be the PCC. In this case, the ACK/NACKfor the downlink data may be transmitted using other cellular bands. Aspecific example will be described below with reference to FIG. 14.

FIG. 14 is an explanatory diagram for describing the second example oftransmission of the ACK/NACK for the downlink data. Referring to FIG.14, the first the L-CC (the first the cellular band) serving as the PCC,the second the L-CC (the second the cellular band) serving as the SCC,and the U-CC (the shared band) serving as the SCC are illustrated. Theterminal device 200 uses the first L-CC (the PCC) to transmit theACK/NACK for the downlink data transmitted by the base station 100 usingthe second L-CC. Further, the terminal device 200 uses the first L-CC(the PCC) to transmit the ACK/NACK for the downlink data transmitted bythe base station 100 using the U-CC. The base station 100 uses thesecond L-CC to perform retransmission of the downlink data transmittedby the base station 100 using the U-CC.

As described above, the base station 100 performs transmission of thedownlink data using the shared band, and performs retransmission of thedownlink data using the cellular band. Accordingly, for example, whenthe shared band is used in the cellular system, it is possible toretransmit the downlink data with a high degree of certainty. Forexample, since the base station 100 is unable to use the shared band, itis possible to prevent a situation in which it is difficult to performthe retransmission of the downlink data. Further, for example, at thetime of the retransmission of the downlink data, collision with signalsof another wireless communication system is prevented.

(Transmission of Downlink Control Information)

As described above, the base station 100 performs transmission of thedownlink data using the shared band, and performs retransmission of thedownlink data using the cellular band. Further, for example, the basestation 100 transmits the downlink control information (DCI) for theretransmission of the downlink data. The control unit 153 controls thetransmission of the DCI for the retransmission of the downlink data.

For example, the DCI indicates the shared band as the shared frequencyband used for the transmission of the downlink data. Thus, for example,the terminal device can recognize that the retransmission is theretransmission of the downlink data transmitted using the shared bandaccording to the retransmission of the downlink data performed by thebase station 100 using the cellular band.

More specifically, since the transmission and retransmission of thedownlink data are commonly performed using the same frequency band, itis not assumed that different frequency bands are used for thetransmission and retransmission of the downlink data. For this reason,when no information is provided to the terminal device, the terminaldevice is unable to associate the transmission of the downlink dataperformed using the shared band with the retransmission of the downlinkdata performed using the cellular band. In this regard, when the DCI forthe retransmission of the downlink data indicates the shared band as theshared frequency band used for the transmission of the downlink data,the terminal device can associate the retransmission of the downlinkdata with the transmission of the downlink data. In other words, theterminal device can recognize that the retransmission is theretransmission of the downlink data transmitted using the shared bandaccording to the retransmission.

(a) Format

The DCI for the retransmission of the downlink data is informationaccording to a predetermined format. In other words, the DCI for theretransmission is information according to a predetermined DCI format.

Shared Frequency Band in which Downlink Data is Transmitted

For example, the predetermined format has a field indicating the sharedfrequency band used for the transmission of the downlink data (theshared frequency band) (hereinafter referred to as a “shared bandfield”).

More specifically, for example, one of two or more bit patterncandidates corresponding to the shared frequency band is included in theshared band field. As an example, there are four shared frequency bands.In this case, the shared band field is a 2-bit field, and one of fourbit pattern candidates (00, 01, 10, 00) corresponding to the sharedfrequency band is included in the shared band field.

For example, the control unit 153 notifies the terminal device of two ormore bit pattern candidates included in the shared band field and theshared frequency bands corresponding to the two or more bit patterns. Asan example, the control unit 153 reports system information indicatingthe two or more bit pattern candidates and the shared frequency band. Asanother example, the control unit 153 may notify the terminal device 200of the two or more bit pattern candidates and the shared frequency bandthrough individual signaling to the terminal device 200. Thus, forexample, the terminal device 200 can specify a specific shared frequencyband based on the bit patterns included in the shared band field.

For example, the shared band field is a U-CC indicator field indicatingthe U-CC used for the transmission of the downlink data.

The CIF of the DCI format merely indicates a frequency band associatedwith the DCI. In other words, the CIF of the DCI format indicates afrequency band used for the transmission/retransmission of the downlinkdata serving as a target of the DCI. For this reason, it should be notedthat it is not possible to use the CIF instead of the shared band field(for example, the U-CC indicator field). Specifically, when thetransmission of the downlink data is performed using the shared band andthe retransmission of the downlink data is performed using the cellularband, the DCI for the retransmission indicates the cellular band but isunable to indicate the shared band in the CIF.

Retransmission Control Process

For example, the predetermined format has a field indicating theretransmission control process for the downlink data (hereinafterreferred to as a “retransmission control process field”).

More specifically, for example, the retransmission control process isthe HARQ process, and the retransmission control process field is a HARQprocess number field.

Thus, for example, the terminal device 200 can specify theretransmission control process for the downlink data according to theretransmission of the downlink data performed by the base station 100using the cellular band.

Transmission/Retransmission of New Data

For example, the predetermined format does not include a fieldindicating whether resource allocation is for transmission of new dataor for retransmission. More specifically, for example, the predeterminedformat does not include a new data indicator (NDI) field.

Accordingly, for example, it is possible to reduce the number of bits ofthe DCI. As a result, radio resources required for the transmission ofthe DCI can be saved. Further, the terminal device 200 can determinethat the resource allocation of the DCI is for the retransmission basedon the fact that the DCI is information according to the predeterminedformat (that is, a format including the shared band field or the like).

Specific Example of Format

FIG. 15 is an explanatory diagram for describing an example of apredetermined DCI format. Referring to FIG. 15, the DCI format isillustrated. The DCI format includes a HARQ process number field and aU-CC indicator field. The HARQ process number field is a fieldindicating the HARQ process for the downlink data, and the U-CCindicator field is a field indicating the U-CC used for the transmissionof the downlink data. The DCI format may further include any other fieldsuch as the carrier indicator or resource block allocation. The DCIformat does not include an NDI field.

(b) Frequency Band Used for Transmission

As described above, the base station 100 performs the transmission ofthe downlink data using the shared band, and performs the retransmissionof the downlink data using the cellular band. Further, the base station100 transmits the DCI for the retransmission of the downlink data usingany one frequency band.

First Example

As a first example, the base station 100 transmits the DCI for theretransmission of the downlink data using the cellular band. This pointwill be described below with reference to FIG. 16 using a specificexample.

FIG. 16 is an explanatory diagram for describing the first example ofthe transmission of the DCI for the retransmission of the downlink data.Referring to FIG. 16, the L-CC (the cellular band) and the U-CC (theshared band) are illustrated. The base station 100 performs thetransmission of the downlink data using the U-CC, and performs theretransmission of the downlink data using the L-CC. In this example, thebase station 100 transmits the DCI for the retransmission of thedownlink data using the L-CC. The U-CC indicator of the DCI indicatesthe U-CC.

As described above, the DCI for the retransmission of the downlink datais transmitted using the cellular band. Accordingly, for example,similarly to the downlink data, the DCI is also transmitted with a highdegree of certainty.

Second Example

As a second example, the base station 100 may transmit the DCI for theretransmission of the downlink data using any other cellular banddifferent from the cellular band. In other words, cross-carrierscheduling may be performed. This point will be described below withreference to FIG. 17 using a specific example.

FIG. 17 is an explanatory diagram for describing the second example ofthe transmission of the DCI for the retransmission of the downlink data.Referring to FIG. 17, the first L-CC (the first cellular band), thesecond L-CC, and the U-CC (the shared band) are illustrated. The basestation 100 performs the transmission of the downlink data using theU-CC, and performs the retransmission of the downlink data using thesecond L-CC. In this example, the base station 100 transmits the DCI forthe retransmission of the downlink data using the first L-CC. In otherwords, cross-carrier scheduling is performed. The carrier indicator (CI)of the DCI indicates the second L-CC, and the U-CC indicator of the DCIindicates the U-CC.

As described above, the DCI for the retransmission of the downlink datamay be transmitted using any other cellular band. Accordingly, forexample, similarly to the downlink data, the DCI is also transmittedwith a high degree of certainty.

Third Example

As a third example, the base station 100 transmits the DCI for theretransmission of the downlink data using the shared band. In otherwords, cross-carrier scheduling may be performed. This point will bedescribed below with reference to FIG. 18 using a specific example.

FIG. 18 is an explanatory diagram for describing the third example ofthe transmission of the DCI for the retransmission of the downlink data.Referring to FIG. 18, the L-CC (the cellular band) and the U-CC (theshared band) are illustrated. The base station 100 performs thetransmission of the downlink data using the U-CC, and performs theretransmission of the downlink data using the L-CC. In this example, thebase station 100 transmits the DCI for the retransmission of thedownlink data using the U-CC. In other words, cross-carrier schedulingis performed. The carrier indicator (CI) of the DCI indicates the L-CC,and the U-CC indicator of the DCI indicates the U-CC.

(c) Example of Control

As described above, the base station 100 transmits the DCI for theretransmission of the downlink data, and the control unit 153 controlsthe transmission of the DCI for the retransmission of the downlink data.

As an example, the control unit 153 controls the transmission of the DCIby performing generation of the DCI and/or the transmission process ofthe DCI (for example, mapping to radio resources or the like).

<4.2. Technical Characteristics Regarding Terminal Device>

Next, technical characteristics regarding terminal device 200 will bedescribed.

(Retransmission Control)

The terminal device 200 (the control unit 243) performs the receivingside process in the retransmission control process according to thetransmission of the downlink data performed by the base station 100using the shared band (that is, the frequency band shared by a pluralityof wireless communication systems including the cellular system).Further, the terminal device 200 (the control unit 243) performs thereceiving side process in the retransmission control process accordingto the retransmission of the downlink data performed by the base station100 using the cellular band (that is, the frequency band for thecellular system).

(a) Retransmission Control Process and Receiving Side Process

For example, the retransmission control process is the HARQ process. Forexample, the retransmission control process is the HARQ process of theHARQ entity of the shared band.

For example, the receiving side process includes error checking of thereceived bit string and the transmission process of the ACK/NACK.Further, for example, the receiving side process includes synthesis ofthe received bit string (for example, the chase combining, theincremental redundancy, or the like).

(b) Specifying of Retransmission Control Process

For example, the terminal device 200 (the control unit 243) specifiesthe retransmission control process based on the DCI for theretransmission of the downlink.

(b-1) DCI

For example, the DCI indicates the shared band as the shared frequencyband used for the transmission of the downlink data. Accordingly, forexample, the terminal device 200 can recognize that the retransmissionis the retransmission of the downlink data transmitted using the sharedband according to the retransmission of the downlink data performed bythe base station 100 using the cellular band.

For example, the DCI indicates the retransmission control process as theretransmission control process for the downlink data. Accordingly, forexample, the terminal device 200 can specify the retransmission controlprocess for the downlink data. As a result, the downlink data can beappropriately processed in the retransmission control process.

(b-2) Predetermined Format

The DCI is information according to a predetermined format. Thepredetermined format has been described above in connection with thebase station 100. Thus a repeated description is omitted.

(c) Determination of Transmission/Retransmission of New Data

For example, the terminal device 200 (the control unit 243) determinesthat the resource allocation of the DCI is for the retransmission basedon the fact that the DCI is information according to the predeterminedformat (that is, a format including the shared band field and theretransmission control process field).

Accordingly, for example, since the DCI may not include the NDI (orsimilar information), it is possible to reduce the number of bits of theDCI. As a result, radio resources required for the transmission of theDCI can be saved.

Further, when the DCI is information according to a format other thanthe predetermined format, the terminal device 200 (the control unit 243)determines whether the resource allocation of the DCI is fortransmission of new data or for retransmission based on the NDI of theDCI.

«5. Flow of Process»

Next, the flow of a process according to an embodiment of the presentdisclosure will be described with reference to FIGS. 19 to 21.

(Process of Base Station 100)

FIG. 19 is a flowchart illustrating an example of a schematic flow of aprocess of the base station 100 according to an embodiment of thepresent disclosure. This process is a process focused on thetransmission and retransmission of the downlink data.

The information acquiring unit 151 acquires the downlink data (S301).The base station 100 transmits the DCI for the transmission of thedownlink data (S303). Further, the base station 100 performs thetransmission of the downlink data using the shared band (that is, thefrequency band shared by a plurality of wireless communication systemsincluding the cellular system) (S305). The control unit 153 controls thetransmission of the DCI and the transmission of the downlink data.

When the ACK for the downlink data is received (YES in S307), theprocess returns to step S301.

When the ACK for the downlink data is not received (NO in S307), thebase station 100 transmits the DCI for the retransmission of thedownlink data (S309). Further, the base station 100 performs theretransmission of the downlink data using the cellular band (that is,the frequency band for the cellular system) (S311). The control unit 153controls the transmission of the DCI and the retransmission of thedownlink data.

When the ACK for the downlink data is received (YES in S313), theprocess returns to step S301. When the ACK for the downlink data is notreceived (NO in S313), the process returns to step S309.

(Process of Terminal Device 200)

(a) First Process

FIG. 20 is a flowchart illustrating an example of a schematic flow of afirst process of the terminal device 200 according to an embodiment ofthe present disclosure. The first process is a process focused on thedownlink data which is transmitted using the shared band (that is, thedownlink data which is retransmitted using the cellular band).

The terminal device 200 (the control unit 243) performs the receivingside process in the retransmission control process according to thetransmission of the downlink data performed by the base station 100using the shared band (that is, the frequency band shared by a pluralityof wireless communication systems including the cellular system) (S321).

When the terminal device 200 transmits the ACK for the downlink data(YES in S323), the process returns to step S321.

When the terminal device 200 does not transmit the ACK for the downlinkdata (NO in S323), the terminal device 200 (the control unit 243)performs the receiving side process in the retransmission controlprocess according to the retransmission of the downlink data performedby the base station 100 using the cellular band (that is, the frequencyband for the cellular system) (S323). Then, the process returns to stepS323.

(b) Second Process

FIG. 21 is a flowchart illustrating an example of a schematic flow of asecond process of the terminal device 200 according to an embodiment ofthe present disclosure. The second process is a process focused on thedownlink data which is transmitted/retransmitted using the cellularband.

The terminal device 200 (the control unit 243) acquires the DCI for thetransmission/retransmission of the downlink data using the cellular band(S331).

For example, the DCI is information according to a predetermined formatincluding the shared band field (for example, the U-CC indicator field)and the retransmission control process field (for example, the HARQprocess number field) (YES in S333). In this case, the terminal device200 (the control unit 243) determines that the resource allocation ofthe DCI is for the retransmission of the downlink data transmitted usingthe shared band (S335). Further, the terminal device 200 (the controlunit 243) specifies the retransmission control process for the downlinkdata based on information of the shared band field and information ofthe retransmission control process field in the DCI (S337). Then, theterminal device 200 (the control unit 243) performs the receiving sideprocess in the retransmission control process (S339). Then, the processends.

For example, when the DCI is not information according to apredetermined format (NO in S333), the terminal device 200 (the controlunit 243) determines that the resource allocation of the DCI is not forthe retransmission of the downlink data transmitted using the sharedband (S341). In other words, the terminal device 200 (the control unit243) determines that the resource allocation of the DCI is forretransmission of the downlink transmitted using the cellular band ortransmission of new downlink data. Further, the terminal device 200 (thecontrol unit 243) specifies the retransmission control process for thedownlink data based on the information of the retransmission controlprocess field in the DCI (S343). Then, the terminal device 200 (thecontrol unit 243) performs the receiving side process in theretransmission control process (S345). Then, the process ends.

Steps S331 to S339 in the second process correspond to step S325 in thefirst process.

«6. Modified Examples»

Next, a modified example of an embodiment of the present disclosure willbe described with reference to FIG. 22.

Overview of Modified Examples

In the example of the above-described embodiment of the presentdisclosure, one base station (the base station 100) performs thetransmission of the downlink data using the shared band, and performsthe retransmission of the downlink data using the cellular band.

On the other hand, in the modified example of the embodiment of thepresent disclosure, carrier aggregation (for example, inter-eNB carrieraggregation) is performed between a first base station and a second basestation. More specifically, for example, the terminal device performswireless communication with the first base station using the cellularband, and performs wireless communication with the second base stationusing the shared band. In this case, the second base station performsthe transmission of the downlink data using the shared band, and thefirst base station performs the retransmission of the downlink datausing the cellular band. For example, the shared band is the SCC for theterminal device 200, and the cellular band is the SCC or the PCC for theterminal device 200.

(Example of First Base Station and Second Base Station)

As an example, the first base station is a base station of a macro cell,and the second base station is a base station of a small celloverlapping the macro cell. A specific example will be described belowwith reference to FIG. 22.

FIG. 22 is an explanatory diagram for describing an example of a basestation according to the modified example of the embodiment of thepresent disclosure. Referring to FIG. 22, a base station 400, a basestation 500, and a terminal device 200 are illustrated. The base station400 is a base station of a macro cell 40, and the base station 500 is abase station of a small cell 50. The terminal device 200 performswireless communication with the base station 400 using the cellularband, and performs wireless communication with the base station 500using the shared band. For example, the base station 500 performs thetransmission of the downlink data to the terminal device 200 using theshared band, and the base station 400 performs the retransmission of thedownlink data using the cellular band.

(Configurations of First Base Station and Second Base Station)

Each of the first base station and the second base station includes anantenna unit, a wireless communication unit, a network communicationunit, a storage unit, and a processing unit, for example, similarly tothe base station 100. Further, for example, the processing unit includesan information acquiring unit and a control unit, similarly to theprocessing unit 150.

(Technical Characteristics of Second Base Station)

(a) Transmission of Downlink Data

The second base station performs the transmission of the downlink datausing the shared band. The control unit of the second base stationcontrols the transmission of the downlink data in a manner that thetransmission of the downlink data is performed using the shared band.

As an example, the control unit controls the transmission of thedownlink data by allocating radio resources (for example, resourceblocks) of the shared band to the terminal device 200 for thetransmission of the downlink data. As a result, the second base stationperforms the transmission of the downlink data using the shared band.

(b) Retransmission of Downlink Data

For example, the first base station performs the retransmission of thedownlink data using the cellular band. The control unit of the secondbase station controls the transmission of the downlink data in a mannerthat the transmission of the downlink data is performed using thecellular band.

As an example, the control unit controls the retransmission of thedownlink data by requesting the first base station to perform theretransmission of the downlink data. In addition or alternatively, thecontrol unit controls the retransmission of the downlink data byproviding the downlink data or data generated based on the downlink data(for example, data generated by encoding the downlink data) to the firstbase station. As a result, the first base station performs theretransmission of the downlink data using the cellular band.

(c) Transmission of Downlink Control Information

For example, the control unit of the second base station controls thetransmission of the DCI for the retransmission of the downlink data.

For example, the first base station transmits the DCI. In this case, asan example, the control unit controls the transmission of the DCI byproviding information used for generation of the DCI (for example, theHARQ process number or the like) to another base station.

The second base station may transmit the DCI. In this case, the controlunit controls the transmission of the DCI by performing generation ofthe DCI and/or the transmission process of the DCI (for example, mappingto radio resources or the like).

(Technical Characteristics of First Base Station)

(a) Retransmission of Downlink Data

For example, the first base station performs the retransmission of thedownlink data using the cellular band. The control unit of the firstbase station controls the retransmission of the downlink data in amanner that the retransmission of the downlink data is performed usingthe cellular band.

As an example, the control unit controls the retransmission of thedownlink data by allocating radio resources (for example, resourceblocks) of the cellular band to the terminal device 200 for thetransmission of the downlink data. As a result, the first base stationperforms the retransmission of the downlink data using the shared band.For example, the information acquiring unit of the first base stationacquires the downlink data or data generated based on the downlink data(for example, data generated by encoding the downlink data).

(b) Transmission of Downlink Control Information

For example, the control unit of the first base station controls thetransmission of the DCI for the retransmission of the downlink data.

For example, the first base station transmits the DCI. In this case, asan example, the control unit controls the transmission of the DCI byperforming generation of the DCI and/or the transmission process of theDCI (for example, mapping to radio resources or the like).

«7. Application Examples»

Technology according to the present disclosure is applicable to variousproducts. For example, the base station 100 (or the base station 400 orthe base station 500) may be implemented as a type of eNB such as amacro eNB or a small eNB. The small eNB may be an eNB to cover a cellsmaller than a macro cell such as a pico eNB, a micro eNB, or a home(femto) eNB. Conversely, the base station 100 (or the base station 400or the base station 500) may also be realized as another type of basestation, such as a Node B or a base transceiver station (BTS). The basestation 100 (or the base station 400 or the base station 500) may alsoinclude a main unit that controls wireless communication (also called abase station device), and one or more remote radio heads (RRHs) placedin a location separate from the main unit. Also, various types ofterminals to be described below temporarily or semi-permanently executea base station function and therefore may operate as the base station100 (or the base station 400 or the base station 500). Further, at leastpart of components of the base station 100 (or the base station 400 orthe base station 500) may be implemented in a base station device or amodule for the base station device.

In addition, the terminal device 200 may be realized as, for example, amobile terminal such as a smartphone, a tablet personal computer (PC), anotebook PC, a portable game console, a portable/dongle-style mobilerouter, or a digital camera, or as an in-vehicle terminal such as a carnavigation device. In addition, the terminal device 200 may also berealized as a terminal that conducts machine-to-machine (M2M)communication (also called a machine-type communication (MTC) terminal).Furthermore, at least a part of constituent elements of the terminaldevice 200 may be realized in a module mounted onboard these terminals(for example, an integrated circuit module configured on a single die).

<7.1. Application Examples Regarding Base Station>

(First Application Example)

FIG. 23 is a block diagram illustrating a first example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied. An eNB 800 includes one or more antennas 810and a base station device 820. Each antenna 810 and the base stationdevice 820 may be connected to each other via an RF cable.

Each of the antennas 810 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the base station device 820 to transmit and receive radiosignals. The eNB 800 may include the multiple antennas 810, asillustrated in FIG. 23. For example, the multiple antennas 810 may becompatible with multiple frequency bands used by the eNB 800. AlthoughFIG. 23 illustrates the example in which the eNB 800 includes themultiple antennas 810, the eNB 800 may also include a single antenna810.

The base station device 820 includes a controller 821, a memory 822, anetwork interface 823, and a wireless communication interface 825.

The controller 821 may be, for example, a CPU or a DSP, and operatesvarious functions of a higher layer of the base station device 820. Forexample, the controller 821 generates a data packet from data in signalsprocessed by the wireless communication interface 825, and transfers thegenerated packet via the network interface 823. The controller 821 maybundle data from multiple base band processors to generate the bundledpacket, and transfer the generated bundled packet. The controller 821may have logical functions of performing control such as radio resourcecontrol, radio bearer control, mobility management, admission control,and scheduling. The control may be performed in corporation with an eNBor a core network node in the vicinity. The memory 822 includes RAM andROM, and stores a program that is executed by the controller 821, andvarious types of control data (such as a terminal list, transmissionpower data, and scheduling data).

The network interface 823 is a communication interface for connectingthe base station device 820 to a core network 824. The controller 821may communicate with a core network node or another eNB via the networkinterface 823. In that case, the eNB 800, and the core network node orthe other eNB may be connected to each other through a logical interface(such as an S1 interface and an X2 interface). The network interface 823may also be a wired communication interface or a wireless communicationinterface for radio backhaul. If the network interface 823 is a wirelesscommunication interface, the network interface 823 may use a higherfrequency band for wireless communication than a frequency band used bythe wireless communication interface 825.

The wireless communication interface 825 supports any cellularcommunication scheme such as LTE and LTE-Advanced, and provides radioconnection to a terminal positioned in a cell of the eNB 800 via theantenna 810. The wireless communication interface 825 may typicallyinclude, for example, a baseband (BB) processor 826 and an RF circuit827. The BB processor 826 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing of layers (such as L1, medium accesscontrol (MAC), radio link control (RLC), and a packet data convergenceprotocol (PDCP)). The BB processor 826 may have a part or all of theabove-mentioned logical functions instead of the controller 821. The BBprocessor 826 may be a memory that stores a communication controlprogram, or a module that includes a processor and a related circuitconfigured to execute the program. Updating the program may allow thefunctions of the BB processor 826 to be changed. The module may be acard or a blade that is inserted into a slot of the base station device820. Alternatively, the module may also be a chip that is mounted on thecard or the blade. Meanwhile, the RF circuit 827 may include, forexample, a mixer, a filter, and an amplifier, and transmits and receivesradio signals via the antenna 810.

The wireless communication interface 825 may include the multiple BBprocessors 826, as illustrated in FIG. 23. For example, the multiple BBprocessors 826 may be compatible with multiple frequency bands used bythe eNB 800. The wireless communication interface 825 may include themultiple RF circuits 827, as illustrated in FIG. 23. For example, themultiple RF circuits 827 may be compatible with multiple antennaelements. Although FIG. 23 illustrates the example in which the wirelesscommunication interface 825 includes the multiple BB processors 826 andthe multiple RF circuits 827, the wireless communication interface 825may also include a single BB processor 826 or a single RF circuit 827.

In the eNB 800 illustrated in FIG. 23, the control unit 153 (and theinformation acquiring unit 151) described with reference to FIG. 7 maybe implemented in the wireless communication interface 825.Alternatively, at least a part of the control unit 153 (and theinformation acquiring unit 151) may be implemented in the controller821. As one example, the eNB 800 is equipped with a module including apart (for example, the BB processor 826) or all of the wirelesscommunication interface 825 and/or the controller 821, and the controlunit 153 (and the information acquiring unit 151) may be implemented inthe module. In this case, the above-mentioned module may store a programfor causing the processor to function as the control unit 153 (and theinformation acquiring unit 151) (in other words, a program for causingthe processor to execute the operation of the control unit 153 (and theinformation acquiring unit 151)) and execute the program. As anotherexample, a program for causing the processor to function as the controlunit 153 (and the information acquiring unit 151) is installed in theeNB 800, and the wireless communication interface 825 (for example, theBB processor 826) and/or the controller 821 may execute the program. Asmentioned above, the eNB 800, the base station device 820, or theabove-mentioned module may be provided as the device including thecontrol unit 153 (and the information acquiring unit 151), and theprogram for causing the processor to function as the control unit 153(and the information acquiring unit 151) may be provided. Also, areadable storage medium storing the above-mentioned program may beprovided. With respect to these points, each of the control units (andthe information acquiring units) of the base station 400 and the basestation 500 described with reference to FIG. 22 are also similar to thecontrol unit 153 (and the information acquiring unit 151).

Also, in the eNB 800 illustrated in FIG. 23, the wireless communicationunit 120 described with reference to FIG. 7 may be implemented in thewireless communication interface 825 (for example, the RF circuit 827).Also, the antenna unit 110 may be implemented in the antenna 810. Also,the network communication unit 130 may be implemented in the controller821 and/or the network interface 823. In these points, the antenna unit,the wireless communication unit, and the network communication unit ofeach of the base station 400 and the base station 500 described abovewith reference to FIG. 22 are similar to the antenna unit 110, thewireless communication unit 120, and the network communication unit 130.

(Second Application Example)

FIG. 24 is a block diagram illustrating a second example of a schematicconfiguration of an eNB to which the technology of the presentdisclosure may be applied. An eNB 830 includes one or more antennas 840,a base station device 850, and an RRH 860. Each antenna 840 and the RRH860 may be connected to each other via an RF cable. The base stationdevice 850 and the RRH 860 may be connected to each other via a highspeed line such as an optical fiber cable.

Each of the antennas 840 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the RRH 860 to transmit and receive radio signals. The eNB 830may include the multiple antennas 840, as illustrated in FIG. 24. Forexample, the multiple antennas 840 may be compatible with multiplefrequency bands used by the eNB 830. Although FIG. 24 illustrates theexample in which the eNB 830 includes the multiple antennas 840, the eNB830 may also include a single antenna 840.

The base station device 850 includes a controller 851, a memory 852, anetwork interface 853, a wireless communication interface 855, and aconnection interface 857. The controller 851, the memory 852, and thenetwork interface 853 are the same as the controller 821, the memory822, and the network interface 823 described with reference to FIG. 23.

The wireless communication interface 855 supports any cellularcommunication scheme such as LTE and LTE-Advanced, and provides wirelesscommunication to a terminal positioned in a sector corresponding to theRRH 860 via the RRH 860 and the antenna 840. The wireless communicationinterface 855 may typically include, for example, a BB processor 856.The BB processor 856 is the same as the BB processor 826 described withreference to FIG. 23, except the BB processor 856 is connected to the RFcircuit 864 of the RRH 860 via the connection interface 857. Thewireless communication interface 855 may include the multiple BBprocessors 856, as illustrated in FIG. 24. For example, the multiple BBprocessors 856 may be compatible with multiple frequency bands used bythe eNB 830. Although FIG. 24 illustrates the example in which thewireless communication interface 855 includes the multiple BB processors856, the wireless communication interface 855 may also include a singleBB processor 856.

Furthermore, in addition to a cellular communication scheme, thewireless communication interface 855 may support a radio LANcommunication scheme. In that case, the wireless communication interface825 may include the BB processor 856 in the radio LAN communicationscheme.

The RRH 860 includes a connection interface 861 and a wirelesscommunication interface 863.

The connection interface 861 is an interface for connecting the RRH 860(wireless communication interface 863) to the base station device 850.The connection interface 861 may also be a communication module forcommunication in the above-mentioned high speed line.

The wireless communication interface 863 transmits and receives radiosignals via the antenna 840. The wireless communication interface 863may typically include, for example, the RF circuit 864. The RF circuit864 may include, for example, a mixer, a filter, and an amplifier, andtransmits and receives radio signals via the antenna 840. The wirelesscommunication interface 863 may include multiple RF circuits 864, asillustrated in FIG. 24. For example, the multiple RF circuits 864 maysupport multiple antenna elements. Although FIG. 24 illustrates theexample in which the wireless communication interface 863 includes themultiple RF circuits 864, the wireless communication interface 863 mayalso include a single RF circuit 864.

In the eNB 830 illustrated in FIG. 24, the control unit 153 (and theinformation acquiring unit 151) described with reference to FIG. 7 maybe implemented in the wireless communication interface 855 and/or thewireless communication interface 863. Alternatively, at least a part ofthe control unit 153 (and the information acquiring unit 151) may beimplemented in the controller 851. As one example, the eNB 830 isequipped with a module including a part (for example, the BB processor856) or all of the wireless communication interface 855 and/or thecontroller 851, and the control unit 153 (and the information acquiringunit 151) may be implemented in the module. In this case, theabove-mentioned module may store a program for causing the processor tofunction as the control unit 153 (and the information acquiring unit151) (in other words, a program for causing the processor to execute theoperation of the control unit 153 (and the information acquiring unit151)) and execute the program. As another example, a program for causingthe processor to function as the control unit 153 (and the informationacquiring unit 151) is installed in the eNB 830, and the wirelesscommunication interface 855 (for example, the BB processor 856) and/orthe controller 851 may execute the program. As mentioned above, the eNB830, the base station device 850, or the above-mentioned module may beprovided as the device including the control unit 153 (and theinformation acquiring unit 151), and the program for causing theprocessor to function as the control unit 153 (and the informationacquiring unit 151) may be provided. Also, a readable storage mediumstoring the above-mentioned program may be provided. With respect tothese points, each of the control units (and the information acquiringunits) of the base station 400 and the base station 500 described withreference to FIG. 22 are also similar to the control unit 153 (and theinformation acquiring unit 151).

Also, in the eNB 830 illustrated in FIG. 24, the wireless communicationunit 120 described, for example, with reference to FIG. 7 may beimplemented in the wireless communication interface 863 (for example,the RF circuit 864). Also, the antenna unit 110 may be implemented inthe antenna 840. Also, the network communication unit 130 may beimplemented in the controller 851 and/or the network interface 853. Inthese points, the antenna unit, the wireless communication unit, and thenetwork communication unit of each of the base station 400 and the basestation 500 described above with reference to FIG. 22 are similar to theantenna unit 110, the wireless communication unit 120, and the networkcommunication unit 130.

<7.2. Application Examples Regarding Terminal Device>

(First Application Example)

FIG. 25 is a block diagram illustrating an example of a schematicconfiguration of a smartphone 900 to which the technology of the presentdisclosure may be applied. The smartphone 900 includes a processor 901,a memory 902, a storage 903, an external connection interface 904, acamera 906, a sensor 907, a microphone 908, an input device 909, adisplay device 910, a speaker 911, a wireless communication interface912, one or more antenna switches 915, one or more antennas 916, a bus917, a battery 918, and an auxiliary controller 919.

The processor 901 may be, for example, a CPU or a system on a chip(SoC), and controls functions of an application layer and another layerof the smartphone 900. The memory 902 includes RAM and ROM, and stores aprogram that is executed by the processor 901, and data. The storage 903may include a storage medium such as a semiconductor memory and a harddisk. The external connection interface 904 is an interface forconnecting an external device such as a memory card and a universalserial bus (USB) device to the smartphone 900.

The camera 906 includes an image sensor such as a charge coupled device(CCD) and a complementary metal oxide semiconductor (CMOS), andgenerates a captured image. The sensor 907 may include a group ofsensors such as a measurement sensor, a gyro sensor, a geomagneticsensor, and an acceleration sensor. The microphone 908 converts soundsthat are input to the smartphone 900 to audio signals. The input device909 includes, for example, a touch sensor configured to detect touchonto a screen of the display device 910, a keypad, a keyboard, a button,or a switch, and receives an operation or an information input from auser. The display device 910 includes a screen such as a liquid crystaldisplay (LCD) and an organic light-emitting diode (OLED) display, anddisplays an output image of the smartphone 900. The speaker 911 convertsaudio signals that are output from the smartphone 900 to sounds.

The wireless communication interface 912 supports any cellularcommunication scheme such as LTE and LTE-Advanced, and performs wirelesscommunication. The wireless communication interface 912 may typicallyinclude, for example, a BB processor 913 and an RF circuit 914. The BBprocessor 913 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing for wireless communication.Meanwhile, the RF circuit 914 may include, for example, a mixer, afilter, and an amplifier, and transmits and receives radio signals viathe antenna 916. The wireless communication interface 912 may also be aone chip module that has the BB processor 913 and the RF circuit 914integrated thereon. The wireless communication interface 912 may includethe multiple BB processors 934 and the multiple RF circuits 914, asillustrated in FIG. 25. Although FIG. 25 illustrates the example inwhich the wireless communication interface 912 includes the multiple BBprocessors 913 and the multiple RF circuits 914, the wirelesscommunication interface 912 may also include a single BB processor 913or a single RF circuit 914.

Further, the wireless communication interface 912 may support othertypes of wireless communication system such as a short range wirelesscommunication system, a near field communication system, and a wirelesslocal area network (LAN) system in addition to the cellularcommunication system, and in this case, the wireless communicationinterface 912 may include the BB processor 913 and the RF circuit 914for each wireless communication system.

Each of the antenna switches 915 switches connection destinations of theantennas 916 among multiple circuits (such as circuits for differentwireless communication schemes) included in the wireless communicationinterface 912.

Each of the antennas 916 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the wireless communication interface 912 to transmit andreceive radio signals. The smartphone 900 may include the multipleantennas 916, as illustrated in FIG. 25. Although FIG. 25 illustratesthe example in which the smartphone 900 includes the multiple antennas916, the smartphone 900 may also include a single antenna 916.

Furthermore, the smartphone 900 may include the antenna 916 for eachwireless communication scheme. In that case, the antenna switches 915may be omitted from the configuration of the smartphone 900.

The bus 917 connects the processor 901, the memory 902, the storage 903,the external connection interface 904, the camera 906, the sensor 907,the microphone 908, the input device 909, the display device 910, thespeaker 911, the wireless communication interface 912, and the auxiliarycontroller 919 to each other. The battery 918 supplies power to blocksof the smartphone 900 illustrated in FIG. 25 via feeder lines, which arepartially shown as dashed lines in the figure. The auxiliary controller919 operates a minimum necessary function of the smartphone 900, forexample, in a sleep mode.

In the smartphone 900 illustrated in FIG. 25, the control unit 243 (andthe information acquiring unit 241) described with reference to FIG. 8may be implemented in the wireless communication interface 912.Alternatively, at least a part of the control unit 243 (and theinformation acquiring unit 241) may be implemented in the processor 901or the auxiliary controller 919. As one example, the smartphone 900 isequipped with a module including a part (for example, the BB processor913) or all of the wireless communication interface 912, the processor901 and/or the auxiliary controller 919, and the control unit 243 (andthe information acquiring unit 241) may be implemented in the module. Inthis case, the above-mentioned module may store a program for causingthe processor to function as the control unit 243 (and the informationacquiring unit 241) (in other words, a program for causing the processorto execute the operation of the control unit 243 (and the informationacquiring unit 241)) and execute the program. As another example, aprogram for causing the processor to function as the control unit 243(and the information acquiring unit 241) is installed in the smartphone900, and the wireless communication interface 912 (for example, the BBprocessor 913), the processor 901, and/or the auxiliary controller 919may execute the program. As mentioned above, the smartphone 900 or theabove-mentioned module may be provided as the device including thecontrol unit 243 (and the information acquiring unit 241), and theprogram for causing the processor to function as the control unit 243(and the information acquiring unit 241) may be provided. Also, areadable storage medium storing the above-mentioned program may beprovided.

Also, in the smartphone 900 illustrated in FIG. 25, the wirelesscommunication unit 220 described, for example, with reference to FIG. 8may be implemented in the wireless communication interface 912 (forexample, the RF circuit 914). Also, the antenna unit 210 may beimplemented in the antenna 916.

(Second Application Example)

FIG. 26 is a block diagram illustrating an example of a schematicconfiguration of a car navigation device 920 to which the technology ofthe present disclosure may be applied. The car navigation device 920includes a processor 921, a memory 922, a global positioning system(GPS) module 924, a sensor 925, a data interface 926, a content player927, a storage medium interface 928, an input device 929, a displaydevice 930, a speaker 931, a wireless communication interface 933, oneor more antenna switches 936, one or more antennas 937, and a battery938.

The processor 921 may be, for example, a CPU or a SoC, and controls anavigation function and another function of the car navigation device920. The memory 922 includes RAM and ROM, and stores a program that isexecuted by the processor 921, and data.

The GPS module 924 uses GPS signals received from a GPS satellite tomeasure a position (such as latitude, longitude, and altitude) of thecar navigation device 920. The sensor 925 may include a group of sensorssuch as a gyro sensor, a geomagnetic sensor, and a barometric sensor.The data interface 926 is connected to, for example, an in-vehiclenetwork 941 via a terminal that is not shown, and acquires datagenerated by the vehicle, such as vehicle speed data.

The content player 927 reproduces content stored in a storage medium(such as a CD and a DVD) that is inserted into the storage mediuminterface 928. The input device 929 includes, for example, a touchsensor configured to detect touch onto a screen of the display device930, a button, or a switch, and receives an operation or an informationinput from a user. The display device 930 includes a screen such as aLCD or an OLED display, and displays an image of the navigation functionor content that is reproduced. The speaker 931 outputs sounds of thenavigation function or the content that is reproduced.

The wireless communication interface 933 supports any cellularcommunication scheme such as LET and LTE-Advanced, and performs wirelesscommunication. The wireless communication interface 933 may typicallyinclude, for example, a BB processor 934 and an RF circuit 935. The BBprocessor 934 may perform, for example, encoding/decoding,modulating/demodulating, and multiplexing/demultiplexing, and performsvarious types of signal processing for wireless communication.Meanwhile, the RF circuit 935 may include, for example, a mixer, afilter, and an amplifier, and transmits and receives radio signals viathe antenna 937. The wireless communication interface 933 may be a onechip module having the BB processor 934 and the RF circuit 935integrated thereon. The wireless communication interface 933 may includethe multiple BB processors 934 and the multiple RF circuits 935, asillustrated in FIG. 26. Although FIG. 26 illustrates the example inwhich the wireless communication interface 933 includes the multiple BBprocessors 934 and the multiple RF circuits 935, the wirelesscommunication interface 933 may also include a single BB processor 934or a single RF circuit 935.

Further, the wireless communication interface 933 may support othertypes of wireless communication system such as a short range wirelesscommunication system, a near field communication system, and a wirelesslocal area network (LAN) system in addition to the cellularcommunication system, and in this case, the wireless communicationinterface 912 may include the BB processor 934 and the RF circuit 935for each wireless communication system.

Each of the antenna switches 936 switches connection destinations of theantennas 937 among multiple circuits (such as circuits for differentwireless communication schemes) included in the wireless communicationinterface 933.

Each of the antennas 937 includes a single or multiple antenna elements(such as multiple antenna elements included in an MIMO antenna), and isused for the wireless communication interface 933 to transmit andreceive radio signals. The car navigation device 920 may include themultiple antennas 937, as illustrated in FIG. 26. Although FIG. 26illustrates the example in which the car navigation device 920 includesthe multiple antennas 937, the car navigation device 920 may alsoinclude a single antenna 937.

Furthermore, the car navigation device 920 may include the antenna 937for each wireless communication scheme. In that case, the antennaswitches 936 may be omitted from the configuration of the car navigationdevice 920.

The battery 938 supplies power to blocks of the car navigation device920 illustrated in FIG. 26 via feeder lines that are partially shown asdashed lines in the figure. The battery 938 accumulates power suppliedform the vehicle.

In the car navigation device 920 illustrated in FIG. 26, the controlunit 243 (and the information acquiring unit 241) described withreference to FIG. 8 may be implemented in the wireless communicationinterface 933. Alternatively, at least a part of the control unit 243(and the information acquiring unit 241) may be implemented in theprocessor 921. As one example, the car navigation device 920 is equippedwith a module including a part (for example, the BB processor 934) orall of the wireless communication interface 933, and/or processor 921,and the control unit 243 (and the information acquiring unit 241) may beimplemented in the module. In this case, the above-mentioned module maystore a program for causing the processor to function as the controlunit 243 (and the information acquiring unit 241) (in other words, aprogram for causing the processor to execute the operation of thecontrol unit 243 (and the information acquiring unit 241)) and executethe program. As another example, a program for causing the processor tofunction as the control unit 243 (and the information acquiring unit241) is installed in the car navigation device 920, and the wirelesscommunication interface 933 (for example, the BB processor 934), and/orthe processor 921 may execute the program. As mentioned above, the carnavigation device 920 or the above-mentioned module may be provided asthe device including the control unit 243 (and the information acquiringunit 241), and the program for causing the processor to function as thecontrol unit 243 (and the information acquiring unit 241) may beprovided. Also, a readable storage medium storing the above-mentionedprogram may be provided.

Also, in the car navigation device 920 illustrated in FIG. 26, thewireless communication unit 220 described, for example, with referenceto FIG. 8 may be implemented in the wireless communication interface 933(for example, the RF circuit 935). Also, the antenna unit 210 may beimplemented in the antenna 937.

The technology of the present disclosure may also be realized as anin-vehicle system (or a vehicle) 940 including one or more blocks of thecar navigation device 920, the in-vehicle network 941, and a vehiclemodule 942. That is, the in-vehicle system (or the vehicle) 940 may beprovided as a device including the control unit 243 (and the informationacquiring unit 241). The vehicle module 942 generates vehicle data suchas vehicle speed, engine speed, and trouble information, and outputs thegenerated data to the in-vehicle network 941.

«8. Conclusion»

The communication devices and the processes according to the embodimentsof the present disclosure have been described with reference to FIGS. 6to 26.

According to the embodiment of the present disclosure, the base station100 includes the control unit 153 that controls the transmission of thedownlink data in a manner that the transmission of the downlink data isperformed using the shared band (that is, the frequency band shared by aplurality of wireless communication systems including the cellularsystem). The control unit 153 controls the retransmission of thedownlink data in a manner that the retransmission of the downlink datais performed using the cellular band (that is, the frequency band forthe cellular system).

Further, according to the embodiment of the present disclosure, theterminal device 200 includes the control unit 243 that performs thereceiving side process in the retransmission control process accordingto the transmission of the downlink data performed by the base stationusing the shared band (that is, the frequency band shared by a pluralityof wireless communication systems including the cellular system). Thecontrol unit 243 performs the receiving side process in theretransmission control process according to the retransmission of thedownlink data performed by the base station using the cellular band(that is, the frequency band for the cellular system).

Accordingly, for example, when the shared band (that is, the frequencyband shared by a plurality of wireless communication systems) is used inthe cellular system, it is possible to retransmit the downlink data witha high degree of certainty.

The preferred embodiment(s) of the present disclosure has/have beendescribed above with reference to the accompanying drawings, whilst thepresent disclosure is not limited to the above examples, of course. Aperson skilled in the art may find various alterations and modificationswithin the scope of the appended claims, and it should be understoodthat they will naturally come under the technical scope of the presentdisclosure.

Although an example in which the cellular system is a system conformingto LTE, LTE-Advanced, or a compliant communication scheme has beendescribed, the present disclosure is not limited to such an example. Forexample, the cellular system may be the one conforming to anothercommunication standard.

Also, the processing steps in each process in this specification are notstrictly limited to execution in a time series following the sequencedescribed in a flowchart or a sequence diagram. For example, theprocessing steps in each process may be executed in a sequence thatdiffers from a sequence described herein as a flowchart or a sequencediagram, and furthermore may be executed in parallel.

Further, it is also possible to create a computer program for making aprocessor (such as, for example, a CPU and a DSP) provided atapparatuses (such as, for example, the base station, the base stationdevice or the module of the base station device, or the terminal deviceor the module for the terminal device) in the present specificationfunction as components of the above-described apparatuses (for example,the control unit) (in other words, a computer program for making theprocessor execute operation of the components of the above-describedapparatuses). Further, it is also possible to provide a recording mediumhaving the above-described computer program recorded therein. Further,it is also possible to provide an apparatus (such as, for example, abase station, a base station device, and a module for the base stationdevice, or a terminal device and a module for a terminal device)including a memory having the above-described computer program storedtherein and one or more processors which can execute the above-describedcomputer program. Further, a method including the operation of thecomponents (for example, the control unit) of the above-describedapparatuses is included in the technique according to the presentdisclosure.

In addition, the advantageous effects described in this specificationare merely for the sake of explanation or illustration, and are notlimiting. In other words, instead of or in addition to the aboveadvantageous effects, technology according to the present disclosure mayexhibit other advantageous effects that are clear to persons skilled inthe art from the description of this specification.

Additionally, the present technology may also be configured as below.

(1)

A device, including:

a control unit configured to control transmission of downlink data in amanner that the transmission of the downlink data is performed using afirst frequency band shared by a plurality of wireless communicationsystems including a cellular system,

wherein the control unit controls retransmission of the downlink data ina manner that the retransmission of the downlink data is performed usinga second frequency band for the cellular system.

(2)

The device according to (1),

wherein the control unit controls transmission of downlink controlinformation for the retransmission of the downlink data, and

the downlink control information indicates the first frequency band as ashared frequency band used for the transmission of the downlink data.

(3)

The device according to (2),

wherein the downlink control information is information according to apredetermined format, and

the predetermined format includes a field indicating the sharedfrequency band used for the transmission of the downlink data.

(4)

The device according to (3),

wherein the control unit notifies a terminal device of two or more bitpattern candidates included in the field and shared frequency bandscorresponding to the two or more bit patterns.

(5)

The device according to (3) or (4),

wherein the predetermined format includes a field indicating aretransmission control process for the downlink data.

(6)

The device according to (5),

wherein the retransmission control process is a hybrid automatic repeatrequest (HARQ) process, and

the field indicating the retransmission control process is a HARQprocess number field.

(7)

The device according to any one of (3) to (6),

wherein the predetermined format does not include a field indicatingwhether resource allocation is for transmission of new data or forretransmission.

(8)

The device according to any one of (1) to (7),

wherein the control unit controls the retransmission of the downlinkdata in a manner that the retransmission of the downlink data isperformed using the second frequency band within a limited period.

(9)

The device according to (8),

wherein the limited period is a period corresponding to an end time ofuse of the second frequency band.

(10)

The device according to (9),

wherein the limited period is a period that starts at a predeterminedtime before the end time.

(11)

The device according to (9),

wherein the limited period is a period that starts from the end time.

(12)

The device according to any one of (1) to (11),

wherein the downlink data is downlink data that is transmitted to aterminal device that supports carrier aggregation,

the first frequency band is a secondary component carrier for theterminal device, and

the second frequency band is a primary component carrier or a secondarycomponent carrier for the terminal device.

(13)

The device according to any one of (1) to (12),

wherein the first frequency band is a channel of a wireless local areanetwork (LAN).

(14)

A method, including:

controlling, by a processor, transmission of downlink data in a mannerthat the transmission of the downlink data is performed using a firstfrequency band shared by a plurality of wireless communication systemsincluding a cellular system; and

controlling, by the processor, retransmission of the downlink data in amanner that the retransmission of the downlink data is performed using asecond frequency band for the cellular system.

(15)

A device, including:

a control unit configured to perform a receiving side process in aretransmission control process according to transmission of downlinkdata performed by a base station using a first frequency band shared bya plurality of wireless communication systems including a cellularsystem,

wherein the control unit performs the receiving side process in theretransmission control process according to retransmission of thedownlink data performed by the base station using a second frequencyband for the cellular system.

(16)

The device according to (15),

wherein the retransmission control process is a hybrid automatic repeatrequest (HARQ) process.

(17)

The device according to (15) or (16),

wherein the control unit specifies the retransmission control processbased on downlink control information for the retransmission of thedownlink data, and

the downlink control information indicates the first frequency band as ashared frequency band used for the transmission of the downlink data,and indicates the retransmission control process as a retransmissioncontrol process for the downlink data.

(18)

The device according to (17),

wherein the downlink control information is information according to apredetermined format, and

the predetermined format includes a field indicating the sharedfrequency band used for the transmission of the downlink data and afield indicating the retransmission control process for the downlinkdata.

(19)

The device according to (18),

wherein the predetermined format does not include a field indicatingwhether resource allocation is for transmission of new data or forretransmission, and

the control unit determines that the resource allocation of the downlinkcontrol information is for the retransmission based on the fact that thedownlink control information is the information according to thepredetermined format.

(20)

A method, including:

performing, by a processor, a receiving side process in a retransmissioncontrol process according to transmission of downlink data performed bya base station using a first frequency band shared by a plurality ofwireless communication systems including a cellular system; and

performing, by the processor, the receiving side process in theretransmission control process according to retransmission of thedownlink data performed by the base station using a second frequencyband for the cellular system.

(21)

A program for causing a processor to:

control transmission of downlink data in a manner that the transmissionof the downlink data is performed using a first frequency band shared bya plurality of wireless communication systems including a cellularsystem; and

control retransmission of the downlink data in a manner that theretransmission of the downlink data is performed using a secondfrequency band for the cellular system.

(22)

A readable recording medium having a program recorded thereon, theprogram causing a processor to:

control transmission of downlink data in a manner that the transmissionof the downlink data is performed using a first frequency band shared bya plurality of wireless communication systems including a cellularsystem; and

control retransmission of the downlink data in a manner that theretransmission of the downlink data is performed using a secondfrequency band for the cellular system.

(23)

A program for causing a processor to:

perform a receiving side process in a retransmission control processaccording to transmission of downlink data performed by a base stationusing a first frequency band shared by a plurality of wirelesscommunication systems including a cellular system; and

perform the receiving side process in the retransmission control processaccording to retransmission of the downlink data performed by the basestation using a second frequency band for the cellular system.

(24)

A readable recording medium having a program recorded thereon, theprogram causing a processor to:

perform a receiving side process in a retransmission control processaccording to transmission of downlink data performed by a base stationusing a first frequency band shared by a plurality of wirelesscommunication systems including a cellular system; and

perform the receiving side process in the retransmission control processaccording to retransmission of the downlink data performed by the basestation using a second frequency band for the cellular system.

REFERENCE SIGNS LIST

-   1 system-   10 cell-   40 macro cell-   50 small cell-   100 base station-   153 control unit-   200 terminal device-   243 control unit-   400 base station-   500 base station

What is claimed is:
 1. A first base station apparatus, comprising: atransceiver; and circuitry configured to: control communication with aterminal device, wherein the terminal device performs carrieraggregation of a primary component carrier and a secondary componentcarrier, a licensed band is the primary component carrier for theterminal device and the first base station apparatus is configured toserve the primary component carrier, and an unlicensed band is thesecondary component carrier for the terminal device and a second basestation apparatus serves the secondary component carrier; determine thata retransmission of downlink data is required, wherein the downlink datais data transmitted on the secondary component carrier from the secondbase station apparatus to the terminal device; control transmission ofdownlink control information to the terminal device, wherein thedownlink control information is information based on a second formatthat is different from a first format, the first format includes a NewData Indicator field, and the second format includes: a first field thatindicates the unlicensed band, and a second field that indicates aretransmission control process for the downlink data; and control theretransmission of the downlink data on the primary component carrierfrom the first base station apparatus to the terminal device based onthe determination that the retransmission of downlink data is required.2. The first base station apparatus according to claim 1, wherein, basedon the transmission of the downlink control information to the terminaldevice, the circuitry is further configured to: notify at least two bitpattern candidates to the terminal device, wherein the at least two bitpattern candidates correspond to the unlicensed band included in thefirst field; and notify, to the terminal device, unlicensed bands thatcorrespond to at least two bit patterns.
 3. The first base stationapparatus according to claim 1, wherein the retransmission controlprocess is a hybrid automatic repeat request (HARQ) process, and thesecond field is a HARQ process number field.
 4. The first base stationapparatus according to claim 1, wherein the second format excludes theNew Data Indicator field for one of transmission of new data orretransmission of the new data.
 5. A method for a first base stationapparatus, the method comprising: controlling, by circuitry,communication with a terminal device, wherein the terminal deviceperforms carrier aggregation of a primary component carrier and asecondary component carrier, a licensed band is the primary componentcarrier for the terminal device and the first base station apparatus isconfigured to serve the primary component carrier, and an unlicensedband is the secondary component carrier for the terminal device and asecond base station apparatus serves the secondary component carrier;determining, by the circuitry, that a retransmission of downlink data isrequired, wherein the downlink data is data transmitted on the secondarycomponent carrier from the second base station apparatus to the terminaldevice; controlling, by the circuitry, transmission of downlink controlinformation to the terminal device, wherein the downlink controlinformation is information based on a second format that is differentfrom a first format, the first format includes a New Data Indicatorfield, and the second format includes: a first field that indicates theunlicensed band, and a second field that indicates a retransmissioncontrol process for the downlink data; and controlling, by thecircuitry, the retransmission of the downlink data on the primarycomponent carrier from the first base station apparatus to the terminaldevice based on the determination that the retransmission of downlinkdata is required.